September 20, 2022 — Night owls may be more prone to diabetes and heart disease than early risers because their bodies aren’t as efficient at burning fat for energy, a new study in Experimental Physiology.
People who wake up early tend to rely more on fat for energy and are often more active during the day, the researchers found. Those who stay up late may not be using as much energy, which means fat can build up on their bodies and increase their risk of diabetes and heart disease.
“This could help medical professionals consider another behavioral factor that contributes to disease risk,” said Steven Malin, PhD, one of the study authors and a metabolism specialist at Rutgers University The guard.
“Night owls have been reported to have a higher risk of obesity, type 2 diabetes and cardiovascular disease compared to early risers,” he said.
Malin and colleagues divided 51 obese middle-aged adults into early risers and night owls based on how they answered a questionnaire about sleep and activity habits. Researchers monitored participants’ activity patterns for a week, testing their body’s energy preferences at rest and while performing moderate- or vigorous-intensity exercise on a treadmill.
The research team found that early risers were more sensitive to insulin levels and burned more fat than night owls, both at rest and during exercise. On the other hand, the night owls were less sensitive to insulin and burned more carbohydrates than fat for energy.
It’s unclear why the metabolic differences exist between early risers and night owls, Malin said. However, one aspect could be a discrepancy between their natural body cycles and the actual times people go to sleep and wake up.
“One possible explanation is that they become out of sync with their circadian rhythm for a variety of reasons, but mostly in adults that would be the work,” he said.
For example, a night owl might prefer to go to bed late, but still need to get up early to go to work or take care of the kids. This could cause them to stop adjusting to their circadian rhythm.
The study results could have implications for sleep-wake patterns, including the health risks of night shift work and annual daylight saving policies, USA Today reported.
“If we encourage a time pattern that’s out of sync with nature, it could exacerbate health risks,” Malin said. “Whether dietary habits or activity can help mitigate these is an area we hope will become clear over time.”